The Contrast None is identified by letter "Z" and occupies the 5th position in the ICD10-PCS procedure code structure.
Below a selection of ICD 10 PCS codes related to B30CZ
Plain Radiography of Bilateral External Carotid Arteries
Plain Radiography of Bi Ext Carotid using Oth Contrast
Plain Radiography of Bi Ext Carotid using L Osm Contrast
Plain Radiography of Bi Ext Carotid using H Osm Contrast